Identification of a carbon dioxide content of a fluid, for example in the air in a living space or in a vehicle passenger compartment, is a frequent task. On the basis of such measurements, for example, ventilation systems can be controlled in energy-efficient fashion.
Patent document U.S. Pat. No. 8,590,366 B2 discusses an apparatus for measuring a carbon dioxide concentration for a vehicle. An interior panel of the vehicle in which a carbon dioxide sensor apparatus is installed has an air entry conduit. The carbon dioxide sensor apparatus contains a light-emitting unit and a light-receiving unit, which are surrounded by a housing. The light emitted from the light-emitting unit passes through air that enters through the light entry conduit, and then strikes the light-receiving unit. The carbon dioxide concentration can be identified by evaluating the received light.
Patent document US 2012/0 028 846 A1 discusses a gas sensor that has a sensor region made of a porous framework for binding a gaseous analyte. A converter converts a change in the sensor region into a detectable property with which an absorbed or adsorbed gaseous analyte is measured.
Patent document DE 102 08 648 A1 discusses a sensor for identifying gases and a method for manufacturing said sensor. The sensor has a measurement electrode and a reference electrode, as well as a polymer layer that is in contact with the gas mixture and with the measurement electrode. A pH-sensitive electrode is provided as a measurement electrode.
Patent document DE 10 2010 014 008 A1 discusses an apparatus for isolating analytes from a expiration volume. The apparatus encompasses a carrier structure for capturing and collecting a breath condensate from the expiration volume.